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--experimental-test-coverage throws error: "TypeError: Cannot read properties of undefined (reading 'line')" #51552
Description
Activity
Unfortunately, this is a known limitation, and source maps are not currently supported: https://nodejs.org/api/test.html#limitations
PR's fixing this are more than welcome@MoLow Are you sure this is a sourcemap issue? I've run into the same thing, and it's fixed by putting an arbitrary import at the top of the file. It seems like the test runner (or coverage collector?) is failing in some way when a module has exports but no imports. Sourcemapping doesn't seem to be involved.
Edit: I've investigated further, and this seems to be file-length related. Adding meaningless comments to the file can make it work/not work. In my testing, I hit upon a 113/114 border: if the file is 113 bytes or fewer, it appears to fail, while 114 bytes or greater seems to succeed. I can make coverage succeed/fail by removing/re-adding a leading newline in the file. Here is a 114 byte file that coverage works for, but removing any single byte will cause it to fail in my testing:
export function sayHello () { console.log('Hello, Console!'); } // These chars are here to get to 114 bytesxxxxxNote there can be no trailing newline and this will work. Removing an x (or any other character) will make it fail.
Replacing one of the final
xes with a trailing newline oddly doesn't work -- but replacing it with 2 newlines does, making the minimum size 115 bytes at that point. I do not know what influences the byte-floor.Node version is v20.10.0.
Reacted by Salman Afzal
Version
v20.11.0
Platform
Linux MyPC 5.15.133.1-microsoft-standard-WSL2 #1 SMP Thu Oct 5 21:02:42 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
Subsystem
No response
What steps will reproduce the bug?
NODE_V8_COVERAGE=./coverage node --test --test-reporter=junit --test-reporter-destination=results.xml --experimental-test-coverage -r ts-node/register test/**/*.spec.tsHow often does it reproduce? Is there a required condition?
100%
What is the expected behavior? Why is that the expected behavior?
Should generate proper coverage
What do you see instead?
content of results.xml:
Additional information
No response